Sexual Dysfunctions
... • During the resolution phase, which may last 30 minutes or longer, the person’s body returns to its resting state. • Men are typically unresponsive to further sexual stimulation for a variable period of time after reaching orgasm. • This is known as the refractory period. • Women, on the other hand ...
... • During the resolution phase, which may last 30 minutes or longer, the person’s body returns to its resting state. • Men are typically unresponsive to further sexual stimulation for a variable period of time after reaching orgasm. • This is known as the refractory period. • Women, on the other hand ...
altruism, sexual selection and causes of male reproductive
... Classic sexual selection theory predicts that males should compete vigorously with one another for access to potential mates (Andersson, 1994; Bateman, 1948; Darwin, 1871; Dewsbury, 2005; Trivers, 1972). Such intrasexual competition is generally believed to be a powerful selective force that, in con ...
... Classic sexual selection theory predicts that males should compete vigorously with one another for access to potential mates (Andersson, 1994; Bateman, 1948; Darwin, 1871; Dewsbury, 2005; Trivers, 1972). Such intrasexual competition is generally believed to be a powerful selective force that, in con ...
Genetic variation in sexual and clonal lineages of
... Sexual reproduction within natural populations of most plants and animals continues to remain an enigma in evolutionary biology. That the enigma persists is not for lack of testable hypotheses but rather because of the lack of suitable study systems in which sexual and asexual females coexist. Here ...
... Sexual reproduction within natural populations of most plants and animals continues to remain an enigma in evolutionary biology. That the enigma persists is not for lack of testable hypotheses but rather because of the lack of suitable study systems in which sexual and asexual females coexist. Here ...
Cooperating to compete: altruism, sexual selection
... 0003-3472/$38.00 Ó 2013 The Authors. Published on behalf of The Association for the Study of Animal Behaviour by Elsevier Ltd. All rights reserved. ...
... 0003-3472/$38.00 Ó 2013 The Authors. Published on behalf of The Association for the Study of Animal Behaviour by Elsevier Ltd. All rights reserved. ...
340Lecture07 - Dr. Stuart Sumida
... However, as in amphioxus, the blastopore does appear in the region of the prospective endoderm. Note the materials that lie on the surface of the blastula that are destined to move inwards through the blastopore: prechordal mesoderm (which will give rise to parts of the braincase), notochordal mesod ...
... However, as in amphioxus, the blastopore does appear in the region of the prospective endoderm. Note the materials that lie on the surface of the blastula that are destined to move inwards through the blastopore: prechordal mesoderm (which will give rise to parts of the braincase), notochordal mesod ...
Asexual Plant Propagation
... 6 to 8 inches in length Taken from year old wood Form callus tissue during the winter Develop roots in the spring ...
... 6 to 8 inches in length Taken from year old wood Form callus tissue during the winter Develop roots in the spring ...
Slide 1 - University of Saskatchewan
... Estrogenic chemicals in the environment have been implicated in causing a variety of adverse effects in exposed organisms. Exposure to estrogens, especially at critical times during sexual development, can cause feminization and/or demasculinization of males of many amphibian species. 17α-ethynylest ...
... Estrogenic chemicals in the environment have been implicated in causing a variety of adverse effects in exposed organisms. Exposure to estrogens, especially at critical times during sexual development, can cause feminization and/or demasculinization of males of many amphibian species. 17α-ethynylest ...
Ape That Thought It Was a Peacock
... In this section, we look at the theoretical underpinnings of the MCFC model—sexual selection theory and parental investment theory—and ask whether these theories apply to human beings. We argue that they do indeed apply, and that they provide a better account of certain psychological sex differences ...
... In this section, we look at the theoretical underpinnings of the MCFC model—sexual selection theory and parental investment theory—and ask whether these theories apply to human beings. We argue that they do indeed apply, and that they provide a better account of certain psychological sex differences ...
WHRHS BIOLOGY K PROFICIENCIES
... 56. Compare and contrast sexual and asexual reproduction. 57. Identify the structure of a chromosome. 58. Explain what happens during each stage of the cell cycle. 59. Compare mitosis and cytokinesis in plant and animal cells. 60. Compare and contrast cancer cells with normal cells. 61. Distinguish ...
... 56. Compare and contrast sexual and asexual reproduction. 57. Identify the structure of a chromosome. 58. Explain what happens during each stage of the cell cycle. 59. Compare mitosis and cytokinesis in plant and animal cells. 60. Compare and contrast cancer cells with normal cells. 61. Distinguish ...
The evolution of song in female birds in Europe
... the evolution of associated neural structures (MacDougallShackleton and Ball 1999; Garamszegi et al. 2005). However, given that song production in females corresponds to certain social and ecological contexts (Langmore 1998), we can expect that interspecific variation in female song should be associ ...
... the evolution of associated neural structures (MacDougallShackleton and Ball 1999; Garamszegi et al. 2005). However, given that song production in females corresponds to certain social and ecological contexts (Langmore 1998), we can expect that interspecific variation in female song should be associ ...
BMC Evolutionary Biology
... Background: The clear dominance of two-gender sex in recent species is a notorious puzzle of evolutionary theory. It has at least two layers: besides the most fundamental and challenging question why sex exists at all, the other part of the problem is equally perplexing but much less studied. Why do ...
... Background: The clear dominance of two-gender sex in recent species is a notorious puzzle of evolutionary theory. It has at least two layers: besides the most fundamental and challenging question why sex exists at all, the other part of the problem is equally perplexing but much less studied. Why do ...
Friends` Influence on Adolescents` First Sexual Intercourse
... that adolescents who perceive that their friends favor postponing sexual intercourse are themselves more likely than others to do so.11 These perceptions may be shaped by a combination of friends’ attitudes and adolescents’ own attitudes.12 Adolescents who are highly involved with their friends may ...
... that adolescents who perceive that their friends favor postponing sexual intercourse are themselves more likely than others to do so.11 These perceptions may be shaped by a combination of friends’ attitudes and adolescents’ own attitudes.12 Adolescents who are highly involved with their friends may ...
The Life Course Development of Human Sexual Orientation: An
... Homosexual behavior is common across cultures but takes on a variety of social forms [Greenberg, 1988; Herdt, 1997]. That is, the notion of sexual orientation understood in much of Western culture through the ‘gay-straight’ dichotomy is extremely rare; few cultures reveal patterns of exclusive homos ...
... Homosexual behavior is common across cultures but takes on a variety of social forms [Greenberg, 1988; Herdt, 1997]. That is, the notion of sexual orientation understood in much of Western culture through the ‘gay-straight’ dichotomy is extremely rare; few cultures reveal patterns of exclusive homos ...
Lineage Selection and the Maintenance of Sex - Université Paris-Sud
... Citation: de Vienne DM, Giraud T, Gouyon P-H (2013) Lineage Selection and the Maintenance of Sex. PLoS ONE 8(6): e66906. doi:10.1371/journal.pone.0066906 Editor: Sergios-Orestis Kolokotronis, Fordham University, United States of America ...
... Citation: de Vienne DM, Giraud T, Gouyon P-H (2013) Lineage Selection and the Maintenance of Sex. PLoS ONE 8(6): e66906. doi:10.1371/journal.pone.0066906 Editor: Sergios-Orestis Kolokotronis, Fordham University, United States of America ...
Biology Textbook - South Sevier High School
... Have you ever asked yourself questions about your surroundings and wondered how or why they are happening? This is science. Science works best when driven by curiosity and innovation. In order for you to experience science in its fullest sense you must take it beyond the textbook and into your every ...
... Have you ever asked yourself questions about your surroundings and wondered how or why they are happening? This is science. Science works best when driven by curiosity and innovation. In order for you to experience science in its fullest sense you must take it beyond the textbook and into your every ...
Evolutionary Psychology - College of Agriculture and Life Sciences
... selection is sometimes encapsulated in the slogan the survival of the fittest, ultimately it is reproductive fitness that counts. It doesn’t matter how well an organism is able to survive. If it fails to pass on its genes, then it is an evolutionary dead end, and the traits responsible for its enhan ...
... selection is sometimes encapsulated in the slogan the survival of the fittest, ultimately it is reproductive fitness that counts. It doesn’t matter how well an organism is able to survive. If it fails to pass on its genes, then it is an evolutionary dead end, and the traits responsible for its enhan ...
Patient Information For Egg Donors And Donor Egg
... The number of embryos replaced will be the decision of the couple and their physician. If there is a surplus of embryos and they are of sufficient quality to freeze, we can do so at an additional fee to the recipients. WHAT GUARANTEES ARE THERE WITH THE DONOR? Women volunteer to donate their eggs an ...
... The number of embryos replaced will be the decision of the couple and their physician. If there is a surplus of embryos and they are of sufficient quality to freeze, we can do so at an additional fee to the recipients. WHAT GUARANTEES ARE THERE WITH THE DONOR? Women volunteer to donate their eggs an ...
Reprint
... not depend on which males they mate with but on how many they mate with. Although these male “phenotypeindependent” costs are probably common, there are other cases where the costs to females do depend on the phenotypes of their mating partners because some male phenotypes are more costly to mate wi ...
... not depend on which males they mate with but on how many they mate with. Although these male “phenotypeindependent” costs are probably common, there are other cases where the costs to females do depend on the phenotypes of their mating partners because some male phenotypes are more costly to mate wi ...
GNEC - Sexuality in Older Adults
... Older adults with HIV/AIDS and other STDs must be taught to follow CDC safe sex practices, as this was not routinely covered in formal education. The use of antiretroviral medications among older adults may be complicated by multiple chronic comorbidities and treatments. HIV-infected patients ...
... Older adults with HIV/AIDS and other STDs must be taught to follow CDC safe sex practices, as this was not routinely covered in formal education. The use of antiretroviral medications among older adults may be complicated by multiple chronic comorbidities and treatments. HIV-infected patients ...
Sexually transmitted infections in polygamous mating systems
... replicating more realistic transmission pathways. This approach is particularly well suited to STIs, as transmission pathways are usually much more clearly defined (i.e. sexual contact) than for non-STIs. However, there are many problems associated with collecting data on real SCNs, including biases ...
... replicating more realistic transmission pathways. This approach is particularly well suited to STIs, as transmission pathways are usually much more clearly defined (i.e. sexual contact) than for non-STIs. However, there are many problems associated with collecting data on real SCNs, including biases ...
Cultural, Historical, and Research Perspectives on Sexuality
... Anthropologists usually classify cultures on the basis of their subsistence patterns, that is, on how the people produce and distribute food and other goods. Anything that affects a society’s subsistence pattern can influence reproduction and thus sexual behavior. Shortages of food, for example, may ...
... Anthropologists usually classify cultures on the basis of their subsistence patterns, that is, on how the people produce and distribute food and other goods. Anything that affects a society’s subsistence pattern can influence reproduction and thus sexual behavior. Shortages of food, for example, may ...
- Developmental Cognitive Neuroscience Lab
... Unusually low testosterone levels that result from removal of the adrenal glands (adrenalectomy), removal of the ovaries (oophorectomy), or as a consequence of menopause, may impair sexual desire in women. Testosterone is effective in restoring sexual desire in these women with abnormally low testos ...
... Unusually low testosterone levels that result from removal of the adrenal glands (adrenalectomy), removal of the ovaries (oophorectomy), or as a consequence of menopause, may impair sexual desire in women. Testosterone is effective in restoring sexual desire in these women with abnormally low testos ...
Taxonomy - Brief facts
... and the nematode, Caenorhabditis elegans, in terms of reduction of the nuclear genome, rapid evolution of the mitochondrial genome, the acquisition of determinate development and simplification of the body plan. The recent genome sequencing of Ciona intestinalis will allow a broad comparative analys ...
... and the nematode, Caenorhabditis elegans, in terms of reduction of the nuclear genome, rapid evolution of the mitochondrial genome, the acquisition of determinate development and simplification of the body plan. The recent genome sequencing of Ciona intestinalis will allow a broad comparative analys ...
Sexual reproduction
Sexual reproduction is a form of reproduction where two morphologically distinct types of specialized reproductive cells called gametes fuse together, involving a female's large ovum (or egg) and a male's smaller sperm. Each gamete contains half the number of chromosomes of normal cells. They are created by a specialized type of cell division, which only occurs in eukaryotic cells, known as meiosis. The two gametes fuse during fertilization to produce DNA replication and the creation of a single-celled zygote which includes genetic material from both gametes. In a process called genetic recombination, genetic material (DNA) joins up so that homologous chromosome sequences are aligned with each other, and this is followed by exchange of genetic information. Two rounds of cell division then produce four daughter cells with half the number of chromosomes from each original parent cell, and the same number of chromosomes as both parents, though self-fertilization can occur. For instance, in human reproduction each human cell contains 46 chromosomes, 23 pairs, except gamete cells, which only contain 23 chromosomes, so the child will have 23 chromosomes from each parent genetically recombined into 23 pairs. Cell division initiates the development of a new individual organism in multicellular organisms, including animals and plants, for the vast majority of whom this is the primary method of reproduction. A species is defined as a taxonomic rank. A species is often defined as the largest group of organisms where two hybrids are capable of reproducing fertile offspring, typically using sexual reproduction, although the species problem encompasses a series of difficult related questions that often come up when biologists define the word species. The evolution of sexual reproduction is a major puzzle because asexual reproduction should be able to outcompete it as every young organism created can bear its own young. This implies that an asexual population has an intrinsic capacity to grow more rapidly with each generation. This 50% cost is a fitness disadvantage of sexual reproduction. The two-fold cost of sex includes this cost and the fact that any organism can only pass on 50% of its own genes to its offspring. One definite advantage of sexual reproduction is that it prevents the accumulation of genetic mutations.Sexual selection is a mode of natural selection in which some individuals out-reproduce others of a population because they are better at securing mates for sexual reproduction. It has been described as ""a powerful evolutionary force that does not exist in asexual populations""Prokaryotes reproduce through asexual reproduction but may display processes similar to sexual reproduction (mechanisms for lateral gene transfer such as bacterial conjugation, transformation and transduction), but they do not lead to reproduction. In prokaryotes, the initial cell has additional or transformed genetic material.